Idea:
SCP-4000 is a device specifically designed to undo time alterations done to the timeline. It removes these changes and their source. SCP-4000 itself would exist in its own separate pocket dimension which the timeline can access, this dimension and everything in it is not effected by timeline changes, meaning that no matter how much a timeline changes, anything in this dimension is not effected. Allowing 4000 to continue existing.

The article would be switch between different versions of the document as SCP-4000 alters the timeline.

Interpretations of timelinesWARNING: The following is my own personal, simplified interpretation of timeline functionality for at least this work in particular.

Similar to other timeline interpretations, each separate time line is made of countless threads, representing each path and action taken etc. These tangle together to form the main timeline. When 4000 removes a time alteration and its source, it removes that thread from the timeline and the remaining ones adapt to the alteration, detangling but attempt remain as close to the original state of the timeline as possible.

The article itself:
The first version of the document would be from a timeline where the world suffered an XK-Class scenario from various time altering beings and phenomena. The Foundation of this timeline build SCP-4000 to undo the time alterations and remove the phenomena that caused them from existence in their timeline. Because of how it functions, SCP-4000 will continue to exist in their timeline even after the events are undone.

In the next document iteration, the XK scenario is reversed, sources of time altering phenomena have been removed by 4000 and the Foundation now discovers SCP-4000 for the first time, at least from their perspective of the time flow (As from their perspective, they don’t remember making it).

They start using 4000 to detect alterations done to their timeline and are able to use 4000 to compare the previous and current state of the timeline, anyalizing the percentage of Keter level anomalies in each one, allowing them to choose which timeline to stick with (Sort of like “Hey guys, according to 4000 we’ve had another change to our timeline again. It says here that in the previous timeline iteration, there were 40% more Keter level anomalies. …Yeah let’s just stick with this timeline…). Eventually though, the timeline is attacked by other timelines, that are trying to destroy it.

The third version of the document is from the perspective of another timeline, describing the timeline we’ve followed so far as an extremely dangerous SCP.
It is revealed that the time alterations removed by SCP-4000 are all sent to and integrated into different timelines once removed from the main timeline. This results in many alternate timelines having to deal with these problems now, some who don’t even have SCP-4000 to fix them. Many Foundations in these other timelines banded together and designated the main timeline as a threat and in their last dying breath, attempted to destroy it to prevent any further destruction to any other timelines.

In the end, the main timeline survives but the world is in a state of complete disrepair, the timeline is significantly damaged and will eventually break. The finale document is that of the current iteration of SCP-4000, it is assumed that was used 2000 to bring life back. The Foundation found SCP-4000 along with an explanation to what has went on previously. But SCP-4000 now works differently. SCP-4000 now removes aspects of other timelines and puts them into its own.

Due to the damage done to the timeline and its need for repair, at some point 4000 was redesigned to remove ‘threads’ from other timelines and integrate them into the main timeline in an attempt to keep it stable. 4000 now removes a single thread from various alternate timelines, but ones that ensure it benefits that timeline rather than cause problems (to prevent another timeline team up fiasco).

As a courtesy to our readers on mobile devices, please collapse long posts. ~Zyn

This idea is fine on a conceptual level, though it has also largely been done already. The Bloom (later the Thorn) from the Resurrection canon essentially serves as this plot device, and even includes the broken timeline and the change in function. 1968 is also somewhat similar to both of these, and is an SCP already.

It's also important to point out that this entry would concentrait more on showing the alternate timelines and exploring what they're like from their perspective. As in 1968 we never actually go to the alternate timeline byt are rather told about it.